The role of primary equipment in the distribution network
Requirements for primary equipment in distribution network automation:
Switching equipment that needs to realize remote signaling function should have at least one set of auxiliary contacts; primary equipment that needs to realize telemetry function should have at least current transformer; switching equipment that needs to realize remote control function should have electric operating mechanism.
The construction and renovation of primary equipment should consider reserving the location, space, working power supply, terminals and interfaces required for installing the distribution terminal.
When it is necessary to obtain power supply for the distribution terminal, a voltage transformer or current transformer should be configured with a capacity that meets the requirements of distribution terminal operation and switch operation.
A backup power supply for distribution terminals should be installed in the distribution network substation to ensure that the distribution terminals can maintain operation for a certain period of time and the switches can be opened and closed once in the event of a main power failure.
Distribution transformer
Distribution transformer (abbreviated as distribution transformer) usually refers to a power transformer with a voltage of 35kV and below, a capacity of less than 2500kVA, and directly supplies power to end users.
effect:
Meet the user's needs for electricity voltage level.
Provide electricity to the general public.
The main components of the distribution transformer are the core and winding. The core is the magnetic circuit of the transformer, and the winding is the circuit of the transformer. The two constitute the core of the transformer.
Circuit breaker
The circuit breaker has a reliable arc extinguishing device, which can not only switch on and off the normal load current, but also connect and bear the short-circuit current for a certain period of time, and can automatically trip under the action of the protection device to cut off the short-circuit fault.
According to the arc extinguishing medium used, circuit breakers can be divided into oil circuit breakers, compressed air circuit breakers, vacuum circuit breakers, SF6 circuit breakers, self-generated gas circuit breakers and magnetic blow circuit breakers. At present, vacuum circuit breakers and SF6 circuit breakers are commonly used in distribution networks.
Load switch
It is used in 10~35kV power supply system and can be used as an independent device or installed in ring network cabinet and other equipment.
It can be operated manually or electrically to break load current and close and carry rated short-circuit current.
The switch has no obvious disconnection point, but the open and closed states of the switch can be accurately indicated by the mechanical linkage device.
Isolating switch
The isolating switch has no arc extinguishing capability and is not allowed to be opened or closed under load. However, when it is disconnected, it can form a visible and obvious breaking point and a safe distance to ensure the personal safety of personnel during power outage maintenance work.
Fuse
Fuse relies on the characteristics of the fuse element or fusible wire. When a short circuit current or an unauthorized high current occurs in the circuit, the heat generated by the current flowing through the fuse element or fusible wire will melt the fuse element or fusible wire, thus breaking the circuit and protecting the electrical equipment.